. When an empty glass bottle is inverted into a bucket of water, the water doesn't enter the bottle due to the air in the bottle. The air takes up room, so that the water can only enter if the air is provided a way out of the bottle which can be only achieved by tilting the bottle slightly.
4. The atmospheric pressure varies with altitude as density of air decreases as we rise up and air becomes rarer. For example: Pressure at sea level is taken as 76 cm of Mercury Column, which is one atmosphere. For every 105m rise in height, pressure decreases by 1 cm of mercury column.
- 2.When we blow air into a balloon, it expands due to the elasticity of the rubber. But after a point, the rubber is expanded to its maximum point and cannot be stretched further.
- 1. The tip of a sewing needle is sharp so that due to its sharp tip, the needle may put the force on a very small area of the cloth, producing a pressure sufficient enough to pierce the cloth being stitched.